Your vessel's drafts are: FWD 14'-11", AFT 16'-01"; and the KG is 24.4 feet. What is the righting moment when the vessel is inclined to 30°? (Use the reference material in Section 1, the blue pages, of the Stability Data Reference Book)
• Use the Stability Data Reference Book cross-curves of stability (KN curves) for the correct mean draft • Relationship between righting arm (GZ), displacement, and righting moment • How to find the vessel’s displacement for the given drafts from hydrostatic data
• What is the proper mean draft for these forward and aft drafts, and which KN curve page in the blue pages does that correspond to? • Once you read the KN value at 30°, how do you convert that into a righting arm (GZ) when KG is given? Think about the formula that adjusts KN using KG. • After you find GZ, what quantity from the hydrostatic tables must you combine with GZ to obtain a righting moment, and in what units?
• Be sure you are using the correct KN curve for the calculated mean draft, not just the nearest whole-foot draft without checking the directions. • Confirm that you are using the correct formula: righting arm (GZ) as a function of KN and KG at a given angle. • Verify that your final righting moment is in foot-tons, checking both displacement units (long tons) and arm units (feet) before matching with the answer choices.
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